Clim. Past, 17, 1455–1482, 2021 https://doi.org/10.5194/cp-17-1455-2021 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. The unidentified eruption of 1809: a climatic cold case Claudia Timmreck1, Matthew Toohey2, Davide Zanchettin3, Stefan Brönnimann4, Elin Lundstad4, and Rob Wilson5 1The Atmosphere in the Earth System, Max Planck Institute for Meteorology, Bundesstr. 53, 20146 Hamburg, Germany 2Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Canada 3Department of Environmental Sciences, Informatics and Statistics, University Ca’ Foscari of Venice, Mestre, Italy 4Institute of Geography Climatology and Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland 5School of Earth & Environmental Sciences, University of St. Andrews, St. Andrews, United Kingdom Correspondence: Claudia Timmreck (
[email protected]) Received: 20 January 2021 – Discussion started: 26 January 2021 Revised: 25 May 2021 – Accepted: 7 June 2021 – Published: 13 July 2021 Abstract. The “1809 eruption” is one of the most recent tions between the N-TREND NH temperature reconstruction unidentified volcanic eruptions with a global climate impact. and the model simulations are weak in terms of the ensemble- Even though the eruption ranks as the third largest since 1500 mean model results, individual model simulations show good with a sulfur emission strength estimated to be 2 times that correlation over North America and Europe, suggesting the of the 1991 eruption of Pinatubo, not much is known of spatial heterogeneity of the 1810 cooling could be due to in- it from historic sources. Based on a compilation of instru- ternal climate variability.